An adsorbent which is produced from porous cellulose beads has the advantages of being safer, exhibiting smaller non-specific adsorption, and being used in broader pH range in comparison with adsorbent produced from other synthetic polymers. In addition, such an adsorbent also has the advantage of having larger mechanical strength, though cellulose is a polysaccharide.
As a use application of an adsorbent which is produced from porous cellulose beads, various medical adsorbents, an adsorbent for chromatography and an affinity adsorbent are exemplified. Among the examples, an affinity adsorbent is used as a medical adsorbent and an adsorbent for purifying a medical antibody, since a target substance can be purified and an undesired substance amount can be reduced efficiently by using an affinity adsorbent. In particular, as a medical adsorbent for treating rheumatism, hemophilia or dilated cardiomyopathy, an adsorbent produced by immobilizing Protein A as an affinity ligand on a porous carrier has attracted attention (for example, Non-patent document 1 and Non-patent document 2).
In addition, it has attracted attention that an adsorbent produced by immobilizing Protein A as an affinity ligand on a porous carrier is used as an adsorbent for purifying a medical antibody by specifically adsorbing an immune globulin, i.e. IgG.
In recent years, since a purification scale has become larger with increasing need for a medical antibody, an adsorbent by which purification at high speed becomes possible and which is produced from porous cellulose beads, in other words, an adsorbent which is produced from porous cellulose beads having high strength, has been required. Under such circumstances, the present inventors filed a patent application by finding that the strength of porous carrier can be enhanced by treating the porous carrier with a long-chain crosslinking agent which has two or more functional groups.
However, when an amount of solid content is increased in order to enhance the strength only, an adsorption amount may be possibly decreased. Accordingly, high-performance porous cellulose beads suitable for producing an adsorbent of which mechanical strength is high and of which adsorption amount is large are required.